100 SEVENTEENTH REPORT. 



The method followed in this work was the original Burrill* 

 method. The experiments were set up as follows: 



Seven cover glasses were sprayed with each dilution of fungicide 

 used, these were allowed to dr}^ at room temperature. These cover 

 glasses were then used as tops to Van Teighem cells, a drop of the 

 spore susi)eusion being placed on each one. 



A separate check was not run for each dilution but a sufficient 

 number were made to be sure of an accurate determination of the 

 average germination. 



The spraying Avas done with an atomizer, taking care not to have 

 too large drops and to cover the slide thoroughl3\ The spores were 

 from a fresh culture on carrot. 



The use of Van Tieghem cells instead of slides Avas to insure 

 against drying out and to enable the spores to be counted with a 

 tlmm. objective, which is necessary in the case of small spores. 



The fungicides were used while fresh and mixed in large enough 

 quantities to insure that they were like those used in the field. 



In counting, six fields of the microscope Avere used on each drop, 

 all spores being counted in each field, thus getting a fair average 

 of the whole. 



The formula for each spray is given AAith the results of the tests 

 in the folloAving pages. 



TESTS WITH BORDEAUX MIXTURE. 



The Bordeaux used in these tests was made up from two stock 

 solutions, one of Chemically pure (Kahlbaum) CaO and the other 

 of CUSO4. These were both made up on a basis of 1 gm. to 50 cc. 

 of water, which is approximately the equivalent of a mixture con- 

 taining S lbs. to 50 gallons of Avater. 



The tAvo stock solutions were diluted separately and then poured 

 together, being shaken for two or three minutes to insure proper 

 mixing of the chemicals. 



The spray Avas not allowed to stand or settle but was placed in 

 a clean atomizer and sprayed on dry coAer slips at once. These 

 had been soaked in cleaning fluid and Avashed thoroughly in distilled 

 Avater before use. 



After they had been sprayed they AA^ere alloAved to dry for at 

 least six hours at room temperature to alloAv for any chemical 

 changes due to atmospheric action, such as might occur when the 

 spray was used in the field. 



Two separate tests were made with Bordeaux mixture at an 

 interval of some time, a new set of stock solutions being used and 



8. BurrMl. T. .T. lU. Sl.n. Bui. 118, p. 5G0, 1907. 



